Many different types of absorbent structures in absorbent articles of the above mentioned kind are previously known. They usually consist of one or more compressed layers of cellulosic fluff pulp, often in combination with superabsorbents, which are polymers with the capacity to absorb water or body liquids many times their own weight. Other types of absorbent structures are airlaid cellulosic fibrous webs which have been bound, with a bonding agent, e.g. latex, heat meltable bonding fibers or the like, dry formed reel pulp, absorbent foam materials etc.
The body liquid is discharged to the absorbent article in a very limited area, the so called wetting point. It shall from there be distributed further to unutilized portions of the absorbent structure. Above all it is desired to have a distribution of liquid in the longitudinal direction of the article, while avoiding spreading toward the longitudinal edges, which can result in edge leakage.
Through EP 0 481 322 there is known an absorbent structure made from a web-shaped absorption material which in its initial position has an even density and thickness in the xy-direction and which has been compressed to a higher density and by that a lower thickness in certain areas. The material is then folded together to form at least two layers which have different densities. In this way an absorbent structure having different densities in the z-direction can be produced.
U.S. Pat. No. 4,027,672 discloses an absorbent body in the form of a pulp structure, in which a pattern of varying basis weights has been created, for example by forming openings in the pulp pad. The pad is then compressed to a substantially uniform thickness, at which the portions having the higher thickness will get a higher density as compared to the portions having the lower density.
U.S. Pat. No. 5,649,916 discloses an absorbent structure comprising three or more superposed absorbent members having an increased wicking capacity along the x- and y-axes relative to the preceding absorbent member. The absorbent members can be in the form of folded web-shaped materials having different widths and different wicking capacities.